Staging: binder: Add more offset validation.

Check that datasize is not smaller than one flat_binder_object.
Check that offsets are aligned.
Check that offsets_size is aligned.
Signed-off-by: Arve Hjønnevåg <arve@android.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/android/binder.c

@@ -1430,10 +1430,19 @@ binder_transaction(struct binder_proc *proc, struct binder_thread *thread,
 		return_error = BR_FAILED_REPLY;
 		goto err_copy_data_failed;
 	}
+	if (!IS_ALIGNED(tr->offsets_size, sizeof(size_t))) {
+		binder_user_error("binder: %d:%d got transaction with "
+			"invalid offsets size, %zd\n",
+			proc->pid, thread->pid, tr->offsets_size);
+		return_error = BR_FAILED_REPLY;
+		goto err_bad_offset;
+	}
 	off_end = (void *)offp + tr->offsets_size;
 	for (; offp < off_end; offp++) {
 		struct flat_binder_object *fp;
-		if (*offp > t->buffer->data_size - sizeof(*fp)) {
+		if (*offp > t->buffer->data_size - sizeof(*fp) ||
+		    t->buffer->data_size < sizeof(*fp) ||
+		    !IS_ALIGNED(*offp, sizeof(void *))) {
 			binder_user_error("binder: %d:%d got transaction with "
 				"invalid offset, %zd\n",
 				proc->pid, thread->pid, *offp);
@@ -1651,7 +1660,9 @@ binder_transaction_buffer_release(struct binder_proc *proc, struct binder_buffer
 		off_end = (void *)offp + buffer->offsets_size;
 	for (; offp < off_end; offp++) {
 		struct flat_binder_object *fp;
-		if (*offp > buffer->data_size - sizeof(*fp)) {
+		if (*offp > buffer->data_size - sizeof(*fp) ||
+		    buffer->data_size < sizeof(*fp) ||
+		    !IS_ALIGNED(*offp, sizeof(void *))) {
 			printk(KERN_ERR "binder: transaction release %d bad"
 					"offset %zd, size %zd\n", debug_id, *offp, buffer->data_size);
 			continue;